Electrical cable used to power down-hole apparatus, such as pumps, in oil wells operate in an extremely hazardous environment. For example, they are constantly subjected to extreme heat, corrosive chemicals, crushing forces, and the possibility of explosive decompression upon removal from the well.
Several prior art patents have addressed this problem including U.S. Pat. Nos. 4,409,431 and 4,453,035 to Neuroth, and disclose structures providing significant protection to the conductors located inside the cables. In U.S. Pat. No. 4,409,431, a plurality of conductors are aligned in a row with substantially I-beam shaped metallic struts being located in between, the entire assembly being covered by an armor tape. In U.S. Pat. No. 4,453,035, a similar construction is provided except that each of the I-beams is formed by two U-shaped struts, each having a lead insert therein. The disclosures of these two patents are hereby incorporated by reference.
While these patents provide significant protection to crushing forces, they do not provide an impervious layer to resist corrosive chemicals. In addition, the use of the lead inserts complicates manufacturing, and the lead inserts are somewhat thin in certain areas.
U.S. Pat. No. 2,690,984 to Crandall et al also attempts to address this problem by providing a cylindrical lead barrier around an insulated conductor; however, this patent does not disclose significant resistance to compressive forces.
Thus, there is a continuing need for improvement in the field of electrical cable used in, for example, oil wells.